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[turbofan] Extend escape analysis to reduce certain CheckMaps.

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Enable the experimental support in escape analysis to deal with
constant-foldable CheckMaps nodes and remove them from the effect
chain w/o blocking the scalar replacement of the object.

BUG=v8:4586,v8:5267
R=tebbi@chromium.org

Review-Url: https://codereview.chromium.org/2964473002
Cr-Commit-Position: refs/heads/master@{#46311}
This commit is contained in:
bmeurer 2017-06-29 03:18:19 -07:00 committed by Commit Bot
parent 73ce185915
commit adf7f54e24
1 changed files with 22 additions and 25 deletions
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47
src/compiler/escape-analysis.cc
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@ -1517,33 +1517,30 @@ void EscapeAnalysis::ProcessCheckMaps(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kCheckMaps);
ForwardVirtualState(node);
Node* checked = ResolveReplacement(NodeProperties::GetValueInput(node, 0));
if (FLAG_turbo_experimental) {
VirtualState* state = virtual_states_[node->id()];
if (VirtualObject* object = GetVirtualObject(state, checked)) {
if (!object->IsTracked()) {
if (status_analysis_->SetEscaped(node)) {
TRACE(
"Setting #%d (%s) to escaped because checked object #%i is not "
"tracked\n",
node->id(), node->op()->mnemonic(), object->id());
}
return;
VirtualState* state = virtual_states_[node->id()];
if (VirtualObject* object = GetVirtualObject(state, checked)) {
if (!object->IsTracked()) {
if (status_analysis_->SetEscaped(node)) {
TRACE(
"Setting #%d (%s) to escaped because checked object #%i is not "
"tracked\n",
node->id(), node->op()->mnemonic(), object->id());
}
CheckMapsParameters params = CheckMapsParametersOf(node->op());
return;
}
CheckMapsParameters params = CheckMapsParametersOf(node->op());
Node* value = object->GetField(HeapObject::kMapOffset / kPointerSize);
if (value) {
value = ResolveReplacement(value);
// TODO(tebbi): We want to extend this beyond constant folding with a
// CheckMapsValue operator that takes the load-eliminated map value as
// input.
if (value->opcode() == IrOpcode::kHeapConstant &&
params.maps().contains(ZoneHandleSet<Map>(
Handle<Map>::cast(OpParameter<Handle<HeapObject>>(value))))) {
TRACE("CheckMaps #%i seems to be redundant (until now).\n",
node->id());
return;
}
Node* value = object->GetField(HeapObject::kMapOffset / kPointerSize);
if (value) {
value = ResolveReplacement(value);
// TODO(tebbi): We want to extend this beyond constant folding with a
// CheckMapsValue operator that takes the load-eliminated map value as
// input.
if (value->opcode() == IrOpcode::kHeapConstant &&
params.maps().contains(ZoneHandleSet<Map>(
Handle<Map>::cast(OpParameter<Handle<HeapObject>>(value))))) {
TRACE("CheckMaps #%i seems to be redundant (until now).\n", node->id());
return;
}
}
}